My last time I went to NZ's West Island, I stopped in Singapore and stayed a night in the Crowne Plaza in Singapore airport.

It was 30k IHG points (so 60k for there and back, or GBP 150ish a night), and I found it well worth it. Very tidy hotel that's about as far away as T5C-T5A from arrivals and accessible via an airtrain, you get to arrive, crash for the night, spend the next day sightseeing, grab your bags and check-in.

Adds 24 hours to your travel time, but so much better than going all the way to the antipodes at once, even in J.